1 #include "private/pthread_support.h"
3 #if defined(GC_PTHREADS) && !defined(GC_SOLARIS_THREADS) \
4 && !defined(GC_IRIX_THREADS) && !defined(GC_WIN32_THREADS) \
5 && !defined(GC_DARWIN_THREADS) && !defined(GC_AIX_THREADS) \
6 && !defined(GC_OPENBSD_THREADS)
14 /* work around a dlopen issue (bug #75390), undefs to avoid warnings with redefinitions */
15 #undef PACKAGE_BUGREPORT
18 #undef PACKAGE_TARNAME
19 #undef PACKAGE_VERSION
20 #include "mono/utils/mono-compiler.h"
22 #ifdef MONO_DEBUGGER_SUPPORTED
23 #include "include/libgc-mono-debugger.h"
27 int nacl_park_threads_now = 0;
28 pthread_t nacl_thread_parker = -1;
30 int nacl_thread_parked[MAX_NACL_GC_THREADS];
31 int nacl_thread_used[MAX_NACL_GC_THREADS];
32 int nacl_thread_parking_inited = 0;
33 int nacl_num_gc_threads = 0;
34 pthread_mutex_t nacl_thread_alloc_lock = PTHREAD_MUTEX_INITIALIZER;
35 __thread int nacl_thread_idx = -1;
36 __thread GC_thread nacl_gc_thread_self = NULL;
43 # define NSIG (MAXSIG+1)
46 # elif defined(__SIGRTMAX)
47 # define NSIG (__SIGRTMAX+1)
54 void GC_print_sig_mask()
59 if (pthread_sigmask(SIG_BLOCK, NULL, &blocked) != 0)
60 ABORT("pthread_sigmask");
61 GC_printf0("Blocked: ");
62 for (i = 1; i < NSIG; i++) {
63 if (sigismember(&blocked, i)) { GC_printf1("%ld ",(long) i); }
70 /* Remove the signals that we want to allow in thread stopping */
71 /* handler from a set. */
72 void GC_remove_allowed_signals(sigset_t *set)
75 if (sigdelset(set, SIGINT) != 0
76 || sigdelset(set, SIGQUIT) != 0
77 || sigdelset(set, SIGABRT) != 0
78 || sigdelset(set, SIGTERM) != 0) {
79 ABORT("sigdelset() failed");
84 /* Handlers write to the thread structure, which is in the heap, */
85 /* and hence can trigger a protection fault. */
86 if (sigdelset(set, SIGSEGV) != 0
88 || sigdelset(set, SIGBUS) != 0
91 ABORT("sigdelset() failed");
96 static sigset_t suspend_handler_mask;
98 word GC_stop_count; /* Incremented at the beginning of GC_stop_world. */
100 #ifdef GC_OSF1_THREADS
101 GC_bool GC_retry_signals = TRUE;
103 GC_bool GC_retry_signals = FALSE;
107 * We use signals to stop threads during GC.
109 * Suspended threads wait in signal handler for SIG_THR_RESTART.
110 * That's more portable than semaphores or condition variables.
111 * (We do use sem_post from a signal handler, but that should be portable.)
113 * The thread suspension signal SIG_SUSPEND is now defined in gc_priv.h.
114 * Note that we can't just stop a thread; we need it to save its stack
115 * pointer(s) and acknowledge.
118 #ifndef SIG_THR_RESTART
119 # if defined(GC_HPUX_THREADS) || defined(GC_OSF1_THREADS)
121 # define SIG_THR_RESTART _SIGRTMIN + 5
123 # define SIG_THR_RESTART SIGRTMIN + 5
126 # define SIG_THR_RESTART SIGXCPU
130 sem_t GC_suspend_ack_sem;
132 static void _GC_suspend_handler(int sig)
136 pthread_t my_thread = pthread_self();
138 # ifdef PARALLEL_MARK
139 word my_mark_no = GC_mark_no;
140 /* Marker can't proceed until we acknowledge. Thus this is */
141 /* guaranteed to be the mark_no correspending to our */
142 /* suspension, i.e. the marker can't have incremented it yet. */
144 word my_stop_count = GC_stop_count;
146 if (sig != SIG_SUSPEND) ABORT("Bad signal in suspend_handler");
149 GC_printf1("Suspending 0x%lx\n", my_thread);
152 me = GC_lookup_thread(my_thread);
153 /* The lookup here is safe, since I'm doing this on behalf */
154 /* of a thread which holds the allocation lock in order */
155 /* to stop the world. Thus concurrent modification of the */
156 /* data structure is impossible. */
157 if (me -> stop_info.last_stop_count == my_stop_count) {
158 /* Duplicate signal. OK if we are retrying. */
159 if (!GC_retry_signals) {
160 WARN("Duplicate suspend signal in thread %lx\n",
166 me -> stop_info.stack_ptr = (ptr_t)GC_save_regs_in_stack();
168 me -> stop_info.stack_ptr = (ptr_t)(&dummy);
171 me -> backing_store_ptr = (ptr_t)GC_save_regs_in_stack();
174 /* Tell the thread that wants to stop the world that this */
175 /* thread has been stopped. Note that sem_post() is */
176 /* the only async-signal-safe primitive in LinuxThreads. */
177 sem_post(&GC_suspend_ack_sem);
178 me -> stop_info.last_stop_count = my_stop_count;
180 /* Wait until that thread tells us to restart by sending */
181 /* this thread a SIG_THR_RESTART signal. */
182 /* SIG_THR_RESTART should be masked at this point. Thus there */
185 me->stop_info.signal = 0;
186 sigsuspend(&suspend_handler_mask); /* Wait for signal */
187 } while (me->stop_info.signal != SIG_THR_RESTART);
188 /* If the RESTART signal gets lost, we can still lose. That should be */
189 /* less likely than losing the SUSPEND signal, since we don't do much */
190 /* between the sem_post and sigsuspend. */
191 /* We'd need more handshaking to work around that, since we don't want */
192 /* to accidentally leave a RESTART signal pending, thus causing us to */
193 /* continue prematurely in a future round. */
195 /* Tell the thread that wants to start the world that this */
196 /* thread has been started. Note that sem_post() is */
197 /* the only async-signal-safe primitive in LinuxThreads. */
198 sem_post(&GC_suspend_ack_sem);
202 GC_printf1("Continuing 0x%lx\n", my_thread);
208 void GC_suspend_handler(int sig)
210 int old_errno = errno;
211 _GC_suspend_handler(sig);
215 static void _GC_restart_handler(int sig)
217 pthread_t my_thread = pthread_self();
220 if (sig != SIG_THR_RESTART) ABORT("Bad signal in suspend_handler");
222 /* Let the GC_suspend_handler() know that we got a SIG_THR_RESTART. */
223 /* The lookup here is safe, since I'm doing this on behalf */
224 /* of a thread which holds the allocation lock in order */
225 /* to stop the world. Thus concurrent modification of the */
226 /* data structure is impossible. */
227 me = GC_lookup_thread(my_thread);
228 me->stop_info.signal = SIG_THR_RESTART;
231 ** Note: even if we didn't do anything useful here,
232 ** it would still be necessary to have a signal handler,
233 ** rather than ignoring the signals, otherwise
234 ** the signals will not be delivered at all, and
235 ** will thus not interrupt the sigsuspend() above.
239 GC_printf1("In GC_restart_handler for 0x%lx\n", pthread_self());
244 # define IF_IA64(x) x
248 /* We hold allocation lock. Should do exactly the right thing if the */
249 /* world is stopped. Should not fail if it isn't. */
250 static void pthread_push_all_stacks()
252 GC_bool found_me = FALSE;
256 /* On IA64, we also need to scan the register backing store. */
257 IF_IA64(ptr_t bs_lo; ptr_t bs_hi;)
258 pthread_t me = pthread_self();
260 if (!GC_thr_initialized) GC_thr_init();
262 GC_printf1("Pushing stacks from thread 0x%lx\n", (unsigned long) me);
264 for (i = 0; i < THREAD_TABLE_SZ; i++) {
265 for (p = GC_threads[i]; p != 0; p = p -> next) {
266 if (p -> flags & FINISHED) continue;
267 if (pthread_equal(p -> id, me)) {
269 lo = (ptr_t)GC_save_regs_in_stack();
274 IF_IA64(bs_hi = (ptr_t)GC_save_regs_in_stack();)
276 lo = p -> stop_info.stack_ptr;
277 IF_IA64(bs_hi = p -> backing_store_ptr;)
279 if ((p -> flags & MAIN_THREAD) == 0) {
281 IF_IA64(bs_lo = p -> backing_store_end);
283 /* The original stack. */
285 IF_IA64(bs_lo = BACKING_STORE_BASE;)
288 GC_printf3("Stack for thread 0x%lx = [%lx,%lx)\n",
289 (unsigned long) p -> id,
290 (unsigned long) lo, (unsigned long) hi);
292 if (0 == lo) ABORT("GC_push_all_stacks: sp not set!\n");
293 # ifdef STACK_GROWS_UP
294 /* We got them backwards! */
295 GC_push_all_stack(hi, lo);
297 GC_push_all_stack(lo, hi);
300 /* Push reg_storage as roots, this will cover the reg context */
301 GC_push_all_stack(p -> stop_info.reg_storage, p -> stop_info.reg_storage + NACL_GC_REG_STORAGE_SIZE);
305 GC_printf3("Reg stack for thread 0x%lx = [%lx,%lx)\n",
306 (unsigned long) p -> id,
307 (unsigned long) bs_lo, (unsigned long) bs_hi);
309 if (pthread_equal(p -> id, me)) {
310 GC_push_all_eager(bs_lo, bs_hi);
312 GC_push_all_stack(bs_lo, bs_hi);
317 if (!found_me && !GC_in_thread_creation)
318 ABORT("Collecting from unknown thread.");
321 void GC_restart_handler(int sig)
323 int old_errno = errno;
324 _GC_restart_handler (sig);
328 /* We hold allocation lock. Should do exactly the right thing if the */
329 /* world is stopped. Should not fail if it isn't. */
330 void GC_push_all_stacks()
332 pthread_push_all_stacks();
335 /* There seems to be a very rare thread stopping problem. To help us */
336 /* debug that, we save the ids of the stopping thread. */
337 pthread_t GC_stopping_thread;
340 #ifdef PLATFORM_ANDROID
342 int android_thread_kill(pid_t tid, int sig)
345 int old_errno = errno;
347 ret = tkill(tid, sig);
357 /* We hold the allocation lock. Suspend all threads that might */
358 /* still be running. Return the number of suspend signals that */
363 int n_live_threads = 0;
367 pthread_t my_thread = pthread_self();
369 GC_stopping_thread = my_thread; /* debugging only. */
370 GC_stopping_pid = getpid(); /* debugging only. */
371 for (i = 0; i < THREAD_TABLE_SZ; i++) {
372 for (p = GC_threads[i]; p != 0; p = p -> next) {
373 if (p -> id != my_thread) {
374 if (p -> flags & FINISHED) continue;
375 if (p -> stop_info.last_stop_count == GC_stop_count) continue;
376 if (p -> thread_blocked) /* Will wait */ continue;
379 GC_printf1("Sending suspend signal to 0x%lx\n", p -> id);
382 #ifndef PLATFORM_ANDROID
383 result = pthread_kill(p -> id, SIG_SUSPEND);
385 result = android_thread_kill(p -> kernel_id, SIG_SUSPEND);
389 /* Not really there anymore. Possible? */
395 ABORT("pthread_kill failed");
400 return n_live_threads;
406 /* Caller holds allocation lock. */
407 static void pthread_stop_world()
415 GC_printf1("Stopping the world from 0x%lx\n", pthread_self());
418 n_live_threads = GC_suspend_all();
420 if (GC_retry_signals) {
421 unsigned long wait_usecs = 0; /* Total wait since retry. */
422 # define WAIT_UNIT 3000
423 # define RETRY_INTERVAL 100000
427 sem_getvalue(&GC_suspend_ack_sem, &ack_count);
428 if (ack_count == n_live_threads) break;
429 if (wait_usecs > RETRY_INTERVAL) {
430 int newly_sent = GC_suspend_all();
433 if (GC_print_stats) {
434 GC_printf1("Resent %ld signals after timeout\n",
438 sem_getvalue(&GC_suspend_ack_sem, &ack_count);
439 if (newly_sent < n_live_threads - ack_count) {
440 WARN("Lost some threads during GC_stop_world?!\n",0);
441 n_live_threads = ack_count + newly_sent;
446 wait_usecs += WAIT_UNIT;
449 for (i = 0; i < n_live_threads; i++) {
450 while (0 != (code = sem_wait(&GC_suspend_ack_sem))) {
451 if (errno != EINTR) {
452 GC_err_printf1("Sem_wait returned %ld\n", (unsigned long)code);
453 ABORT("sem_wait for handler failed");
458 GC_printf1("World stopped from 0x%lx\n", pthread_self());
460 GC_stopping_thread = 0; /* debugging only */
466 GC_printf1("pthread_stop_world: num_threads %d\n", nacl_num_gc_threads - 1);
468 nacl_thread_parker = pthread_self();
469 nacl_park_threads_now = 1;
472 #define NACL_PARK_WAIT_NANOSECONDS 100000
473 int num_threads_parked = 0;
476 /* Check the 'parked' flag for each thread the GC knows about */
477 for (i = 0; i < MAX_NACL_GC_THREADS && num_used < nacl_num_gc_threads; i++) {
478 if (nacl_thread_used[i] == 1) {
480 if (nacl_thread_parked[i] == 1) {
481 num_threads_parked++;
485 /* -1 for the current thread */
486 if (num_threads_parked >= nacl_num_gc_threads - 1)
489 ts.tv_nsec = NACL_PARK_WAIT_NANOSECONDS;
491 GC_printf1("sleeping waiting for %d threads to park...\n", nacl_num_gc_threads - num_threads_parked - 1);
504 #define NACL_STORE_REGS() \
512 asm("mov %%esp, %0" : "=m" (nacl_gc_thread_self->stop_info.stack_ptr));\
513 memcpy(nacl_gc_thread_self->stop_info.reg_storage, nacl_gc_thread_self->stop_info.stack_ptr, NACL_GC_REG_STORAGE_SIZE * sizeof(ptr_t));\
514 asm("add $48, %esp");\
515 asm("add %r15, %rsp");\
520 #define NACL_STORE_REGS() \
526 asm("mov %%esp, %0" : "=m" (nacl_gc_thread_self->stop_info.stack_ptr));\
527 memcpy(nacl_gc_thread_self->stop_info.reg_storage, nacl_gc_thread_self->stop_info.stack_ptr, NACL_GC_REG_STORAGE_SIZE * sizeof(ptr_t));\
528 asm("add $16, %esp");\
533 void nacl_pre_syscall_hook()
536 if (nacl_thread_idx != -1) {
538 nacl_gc_thread_self->stop_info.stack_ptr = (ptr_t)(&local_dummy);
539 nacl_thread_parked[nacl_thread_idx] = 1;
543 void nacl_post_syscall_hook()
545 /* Calling __nacl_suspend_thread_if_needed() right away should guarantee we don't mutate the GC set. */
546 __nacl_suspend_thread_if_needed();
547 if (nacl_thread_idx != -1) {
548 nacl_thread_parked[nacl_thread_idx] = 0;
552 void __nacl_suspend_thread_if_needed() {
553 if (nacl_park_threads_now) {
554 pthread_t self = pthread_self();
556 /* Don't try to park the thread parker. */
557 if (nacl_thread_parker == self)
560 /* This can happen when a thread is created */
561 /* outside of the GC system (wthread mostly). */
562 if (nacl_thread_idx < 0)
565 /* If it was already 'parked', we're returning from a syscall, */
566 /* so don't bother storing registers again, the GC has a set. */
567 if (!nacl_thread_parked[nacl_thread_idx]) {
569 nacl_gc_thread_self->stop_info.stack_ptr = (ptr_t)(&local_dummy);
571 nacl_thread_parked[nacl_thread_idx] = 1;
572 while (nacl_park_threads_now)
574 nacl_thread_parked[nacl_thread_idx] = 0;
576 /* Clear out the reg storage for next suspend. */
577 memset(nacl_gc_thread_self->stop_info.reg_storage, 0, NACL_GC_REG_STORAGE_SIZE * sizeof(ptr_t));
583 /* Caller holds allocation lock. */
587 GC_notify_event (GC_EVENT_PRE_STOP_WORLD);
588 /* Make sure all free list construction has stopped before we start. */
589 /* No new construction can start, since free list construction is */
590 /* required to acquire and release the GC lock before it starts, */
591 /* and we have the lock. */
592 # ifdef PARALLEL_MARK
593 GC_acquire_mark_lock();
594 GC_ASSERT(GC_fl_builder_count == 0);
595 /* We should have previously waited for it to become zero. */
596 # endif /* PARALLEL_MARK */
598 #ifdef MONO_DEBUGGER_SUPPORTED
599 if (gc_thread_vtable && gc_thread_vtable->stop_world)
600 gc_thread_vtable->stop_world ();
603 pthread_stop_world ();
604 # ifdef PARALLEL_MARK
605 GC_release_mark_lock();
608 GC_notify_event (GC_EVENT_POST_STOP_WORLD);
611 /* Caller holds allocation lock, and has held it continuously since */
612 /* the world stopped. */
613 static void pthread_start_world()
616 pthread_t my_thread = pthread_self();
618 register GC_thread p;
619 register int n_live_threads = 0;
624 GC_printf0("World starting\n");
627 GC_notify_event (GC_EVENT_PRE_START_WORLD);
629 for (i = 0; i < THREAD_TABLE_SZ; i++) {
630 for (p = GC_threads[i]; p != 0; p = p -> next) {
631 if (p -> id != my_thread) {
632 if (p -> flags & FINISHED) continue;
633 if (p -> thread_blocked) continue;
636 GC_printf1("Sending restart signal to 0x%lx\n", p -> id);
639 #ifndef PLATFORM_ANDROID
640 result = pthread_kill(p -> id, SIG_THR_RESTART);
642 result = android_thread_kill(p -> kernel_id, SIG_THR_RESTART);
646 /* Not really there anymore. Possible? */
652 ABORT("pthread_kill failed");
659 GC_printf0 ("All threads signaled");
662 for (i = 0; i < n_live_threads; i++) {
663 while (0 != (code = sem_wait(&GC_suspend_ack_sem))) {
664 if (errno != EINTR) {
665 GC_err_printf1("Sem_wait returned %ld\n", (unsigned long)code);
666 ABORT("sem_wait for handler failed");
672 GC_notify_event (GC_EVENT_POST_START_WORLD);
674 GC_printf0("World started\n");
678 GC_printf0("World starting\n");
680 nacl_park_threads_now = 0;
684 void GC_start_world()
686 #ifdef MONO_DEBUGGER_SUPPORTED
687 if (gc_thread_vtable && gc_thread_vtable->start_world)
688 gc_thread_vtable->start_world();
691 pthread_start_world ();
694 static void pthread_stop_init() {
696 struct sigaction act;
698 if (sem_init(&GC_suspend_ack_sem, 0, 0) != 0)
699 ABORT("sem_init failed");
701 act.sa_flags = SA_RESTART;
702 if (sigfillset(&act.sa_mask) != 0) {
703 ABORT("sigfillset() failed");
705 GC_remove_allowed_signals(&act.sa_mask);
706 /* SIG_THR_RESTART is set in the resulting mask. */
707 /* It is unmasked by the handler when necessary. */
708 act.sa_handler = GC_suspend_handler;
709 if (sigaction(SIG_SUSPEND, &act, NULL) != 0) {
710 ABORT("Cannot set SIG_SUSPEND handler");
713 act.sa_handler = GC_restart_handler;
714 if (sigaction(SIG_THR_RESTART, &act, NULL) != 0) {
715 ABORT("Cannot set SIG_THR_RESTART handler");
718 /* Inititialize suspend_handler_mask. It excludes SIG_THR_RESTART. */
719 if (sigfillset(&suspend_handler_mask) != 0) ABORT("sigfillset() failed");
720 GC_remove_allowed_signals(&suspend_handler_mask);
721 if (sigdelset(&suspend_handler_mask, SIG_THR_RESTART) != 0)
722 ABORT("sigdelset() failed");
724 /* Check for GC_RETRY_SIGNALS. */
725 if (0 != GETENV("GC_RETRY_SIGNALS")) {
726 GC_retry_signals = TRUE;
728 if (0 != GETENV("GC_NO_RETRY_SIGNALS")) {
729 GC_retry_signals = FALSE;
732 if (GC_print_stats && GC_retry_signals) {
733 GC_printf0("Will retry suspend signal if necessary.\n");
739 /* We hold the allocation lock. */
742 #ifdef MONO_DEBUGGER_SUPPORTED
743 if (gc_thread_vtable && gc_thread_vtable->initialize)
744 gc_thread_vtable->initialize ();
747 pthread_stop_init ();
750 #ifdef MONO_DEBUGGER_SUPPORTED
752 GCThreadFunctions *gc_thread_vtable = NULL;
755 GC_mono_debugger_get_stack_ptr (void)
759 me = GC_lookup_thread (pthread_self ());
760 return &me->stop_info.stack_ptr;